This week’s theme-title is a pun. We’ll be talking about words related to parts of the face.

sclera – the white of the eyeball

For the family visit, she … she moisturized her skin, and at the last minute, she put Visine in her eyes until the sclera were parchment white. Only her little grand-daughter … had noticed.– Jacqueline Sheehan, Lost & Found

We get this from the Greek for ‘hard’, which in turn goes back their term for Greek for ‘to dry up, parch’. More body-words, from the same ‘hard’ and ‘dry’ roots, are skeleton and arteriosclerosis, ‘hardening of the arteries’ and sclerosis, the more general term for ‘abnormal hardening of tissues’.

I mention this last because it has a much more interesting figurative use, to mean “rigidity, excessive resistance to change”. It’s been used to refer to theater (old-fashioned and sclerotic), transportation (the traffic [gets] more sclerotic), and governments (sclerotic tax laws). And here’s a spin-off coined (apparently by German economist Herbert Giersch) in the 1980s:

… Western Europe, where political business leaders have worried about their countries' loss of dynamism, failure to create jobs or cure unemployment - an ailment known as Eurosclerosis.– New York Times, April 9, 1986

Anyone who has ever dissected an eyeball knows that the sclera is appropriately named. I used to teach a lab in which we dissected bovine eyes. It's like cutting open a racquetball. I would toss a whole one on the floor and challenge one of the students to stand on it. They can usually support at least 150 lbs before rupturing.

My friend in Medical School reported on an incident when he and his classmates were paired off to do dissections, two students and a ... cadaver ... per cubicle. Concentrating that day on the Genito-urinary systems. From one of the cubicles came the voice of a female student saying, "I always thought it had a bone in it."

sinciput – the forehead (also, the upper half of the skull)[From Latin, meaning ‘semi-head’. A truly obscure word for the same thing is bregma. Compare occiput – the back of the skull.]

A fortunate accident happened to me when I was a very little boy. A good-hearted old Irish nurse took me up one day by the heels, when I was making more noise than was necessary, and swinging me round two or three times, d-----d my eyes for “a skreeking little spalpeen,” and then knocked my head into a cocked hat against the bedpost. A bump arose at once on my sinciput … – Edgar Allen Poe, The Business Man (excepted)

nares – nostrils Illustrated by two quotes with unusual perspectives. In the first, a fish insults a swan. In the second, we consider how the Invisible Man’s innards work.

. . .“Look,” said the Wart, “it is the poor swan with the deformed leg. It can only paddle with one leg, and the other side of it is hunched.. . .“Nonsense,” said the swan snappily, putting its head into the water rand giving them a frown with its black nares. “Swans like to rest in this position, and you can keep your keep your fishy sympathy to yourself, so there.” It continued to glare at them from up above, … until they were out of sight.– T. H. White, The Once and Future King

After he had done eating, … the Invisible Man demanded a cigar. … It was strange to see him smoking; his mouth, and throat, pharynx and nares, became visible as a sort of whirling smoke cast. – H.G. Wells, The Invisible Man

edentate – toothless[also refers to certain mammals, such as armadillos, that are toothless or nearly so]

Speaking of teeth: There have never been dentists on Santa Rosalia or any of the other human colonies in the Galápagos Islands. As would have been the case a million years ago, a typical colonist can expect to be edentate by the time he or she is thirty years old, having suffered many skull-cracking toothaches on the way.– Kurt Vonnegut, Galápagos

(Would it be unkind to mention that the species homo sapiens is a good deal less than a million years old?)

It's noisy, and to block out the noise you stick your finger in your ear, palm forward. Your fingerpad presses against a stiff flap of cartilage. Who'd have thought that it had a name? This is not an easy word to work into a conversation!

tragus – the bump of cartilage in front of the ear-hole[from Greek for "male goat", supposedly so named for the tuft of hair which grows there]

… the man with the cell phone repeated it with harried precision, his free index finger applied to the tragus of his other ear, keeping out the noise of the crowd … – Liam Durcan, Garcia's Heart

Dictionaries conflict on today’s word. AHD has it as a horse-word (a sudden, violent check of a horse, by drawing the reins suddenly), but to Merriam Webster it pertains to the eyes. Neither mentions the other’s sense. For our theme, we focus on the eyes.

saccade – a brief, rapid eye-movement from one position of rest to another, either voluntary (as in reading) or involuntary

[His father lies, barely alive:] I sit down next to my father on his cot. I take his hand in mine and put it on the crown of my head. My father’s eye makes quick birdlike saccades up and down.– Adam Davies, Goodbye Lemon (ellipses omitted)

Beep! A new [email] message had just arrived. The sender’s address was -- My God … He opened the message, and his eyes flew all over it in mad saccades, trying to absorb it as a gestalt. And then, his pulse racing, he re-read it carefully, from top to bottom.– Robert J. Sawyer, Rollback

OED reveals why those two dictionaries conflict. A saccade is that eye-movement or, more generally, any “jerk or jerky movement” – whether “horsy” or not. Here’s an example of that broader sense:

I felt the corners of my mouth saccade. Hell, he had a gun. He could take whatever he wanted.– Leo L. Sullivan, Life

Does anyone know the difference between this and nystagmus? I would define jerky eye movements, as in this definition, as nystagmus, and I haven't heard of saccade before. Here is an online definition for nystagmus: " Involuntary movements of the eyes, often noted as shaky or wiggly movement." Perhaps the the difference is that saccade can be voluntary; nystagmus is always abnormal.

Perhaps the the difference is that saccade can be voluntary; nystagmus is always abnormal.

Not exactly. Everyone with normal vision is saccading once or twice every second; you cannot will them to cease completely. If they are suppressed (mechanically or pharmacologically) you "grey out" and only see patches of the scene or parts where things are moving. Your eye needs to be constantly moving in order to properly see.

The eye movements in nystagmus may or may not be saccades (that is, driven by the saccadic control system of the brain) depending on the type of nystagmus, but voluntary nystagmus, the ability to rapidly vibrate one's eyes side-to-side at will (which I can do, by the way), appears to be regular saccades rapidly cycled with little or no refractory period between them. It used to freak kids out in grade school.

Originally posted by Kalleh:Does anyone know the difference between this and nystagmus?

Saccades refer to any sudden movement of the eyeballs whether conscious or unconscious, normal or abnormal.

Nystagmus is generally an abnormal (pathological) movement of the eyeballs, but has many different and complex patterns depending on direction of primary gaze, speed and type of movement, etc. It can even be dysconjugate—affecting one eye more than the other. It can be congenital, or, caused by a large number of diseases in various sites in the brain, and also induced by drugs, including alcohol. Too big a topic for a blog.

Saccades refer to any sudden movement of the eyeballs whether conscious or unconscious, normal or abnormal.

This is not correct, at least not among people who publish about these things. Saccades are specific, high-velocity, time-optimized eye movements that redirect fixation. They can be distinguished by their angle/maximum velocity profile from other kinds of eye movements, and they are produced by a particular control center in the brain.

An interesting word, first coined (in the eye movement sense) by Louis Émile Javal, a French ophthalmologist, in the late 19th century, from an equestrian term, from French saquer 'to jerk, pull abruptly' (< VL verb *saccare, supposedly related to sac 'sack, bag', but I couldn't track that down). (Extra: Javal became totally blind by 1900 and was an Esperanto enthusiast, being a friend of L L Zamenhof, who was also an eye doctor.)

Your 19th-century dating is interesting z. OED has 1953 and MW has 1938 (each for the eye-moment sense). But perhaps it was 19th century in French, and didn't come into English until later. Do you have any more details of the 19th-century usage?

This week quite a few readers have written asking me, “Are you going to do my favorite body-word?” Every one of them had the same favorite, and it’s one of my favorites too. How curious; I wonder why so many of us like it.

philtrum – the vertical groove from the base of the nose to the upper lip[from Greek philein "to love; to kiss"]

Even when he was clean-shaven, a five o'clock shadow stippled his face, especially on the philtrum between nose and mouth.– Diane Ackerman, The Zookeeper's Wife

A friend of ours is a paramedic. When one of her patients is about to faint, she pinches the patient's philtrum – the fleshy part between the upper lip and nose. That prevents the faint from happening.– Joan Wilen and Lydia Wilen, More Chicken Soup & Other Folk Remedies

Originally posted by pearce:Nystagmus is generally an abnormal (pathological) movement of the eyeballs....it can be congenital, or, caused by a large number of diseases in various sites in the brain, and also induced by drugs, including alcohol. Too big a topic for a blog.

I seem to recall learning somewhere that it often presents in persons undergoing the last stages of starvation.

People like me! Well, not me, exactly, but my dissertation adviser made a career of it (see esp. #168). People who study vision, or eye movements, or neurology, or ophthalmology. There's a whole neurological system that drives these eye movements, and we would like to understand how it works. And they are crucial for our visual system to work properly, so we'd like to understand that business, too.

Saccades refer to any sudden movement of the eyeballs whether conscious or unconscious, normal or abnormal.

This is not correct, at least not among people who publish about these things. Saccades are specific, high-velocity, time-optimized eye movements that redirect fixation. They can be distinguished by their angle/maximum velocity profile from other kinds of eye movements, and they are produced by a particular control center in the brain.

Neveu, your description is correct, but is entirely consistent with my deliberately non-technical one liner! There are many detailed publications and explanations, but for anyone curious enough to be interested in the technicalities, a very brief summary might be:

The major conjugate eye movement systems are saccades and pursuit. The saccadic system controls rapid eye movement and maintains fixation (foveation) on the object of regard. Horizontal saccades are controlled by contralateral frontal eye fields in the frontal lobe. The right frontal lobe controls saccades to the left, and the left frontal lobe controls horizontal saccades to the right.The pursuit system controls smooth tracking to follow slow-moving objects. The pursuit movements are controlled by the parietal lobe on the same side (ie, right pursuit is driven by the right parietal lobe, and left pursuit is driven by the left parietal lobe). Most voluntary eye movements are a combination of saccade and pursuit eye movements.Saccades can be tested by asking a person to move his or her eyes in a particular direction. Separating saccades from smooth pursuit may be clinically important. Smooth pursuit may be irregular in brainstem-cerebellar disease, and catch-up saccades may be required. In certain syndromes, upgaze saccades may be affected more than upward smooth pursuit early in the disease. In patients with small pontine strokes involving purely the paramedian pontine reticular formation (PPRF), saccades may be affected and smooth pursuit relatively preserved, because the fibers of the latter eye-movement system do not synapse in the PPRF.

Nystagmus is defined as a periodic rhythmic ocular oscillation of the eyes. The oscillations may be sinusoidal and of approximately equal amplitude and velocity (pendular nystagmus) or, more commonly, with a slow initiating phase and a fast corrective phase (jerk nystagmus).Nystagmus may be unilateral or bilateral, but, when the nystagmus appears unilateral, it is more often asymmetrical rather than truly unilateral. Nystagmus may be conjugate or disconjugate (dissociated). It may be horizontal, vertical, torsional (rotary), or any combination of these movements superimposed upon each other.

The detailed analysis of these eye movements is invaluable in location and diagnosis of diseases of the brain and brainstem.

Apparently I just didn't study eyes enough, as clearly saccode is a medical term.

Pearce had said that "generally" nystagmus is pathologic (I had thought it always was), though "saccades" seem to be more general, including both pathologic and normal movements. Yet, neveu says that any old jerky movement isn't a saccade. So that conclusion about saccades being more general might not be correct; is it? Is any old jerky movement nystagmus then?

Not always. Gazing at the scenery from the side window a moving train can induce optokinetic nystagmus, and there's also voluntary nystagmus.

quote:

though "saccades" seem to be more general, including both pathologic and normal movements

Maybe saccade used to include pathologic movements, but now it almost exclusively refers to normal eye movements. The presence of saccades can be pathological, but they are normal saccades. For example, schizophrenics tend track moving objects using saccadic eye movements rather than smooth pursuit movements, jumping ahead to where the object will be, briefly fixating then jumping again, instead of smoothly following the target like a normal subject.

quote:

So that conclusion about saccades being more general might not be correct; is it?

Originally posted by neveu:…Maybe saccade used to include pathologic movements, but now it almost exclusively refers to normal eye movements.

Showing off one's professional knowledge is not generally a laugh, nor useful intelligence to those not in need. I really don't think it apt to indulge in such a specialised and technical physiological/neurological topic in this setting, but let's be correct.

in nystagmus,which is usually pathological, the primary eye movement is an oscillation; but it swings back rapidly, and this is called a corrective saccade. So it's wrong to say that saccades almost exclusively refer to normal eye movements, though saccades are an element in normal eye movements, especially fixation et.c etc.

nevau, pearce, this discussion is hard for me to follow, but it would be no surprise if the definition I gave isn’t quite right. That's understandable when a term specific-to-a-field is defined by someone not personally familiar with that field. For example, I’ve found that OED not-infrequently err when defining terms from field (e.g., basketball) that I happen to know well.

Here are OED’s definitions of the terms you’re talking about. If (as I think you’re saying) those definitions are not quite right, could you please provide a corrected text, plus a brief explanation of the change of the sort a layman could follow? I’ll pass it on to the folks at OED.

saccade – A brief, rapid movement of the eye from one position of rest to another, whether voluntary (as in reading) or involuntary (as when a point is fixated).nynstagmus – Involuntary, rapid, oscillating movement of the eyeballs (most commonly from side to side); an instance or type of this.

Showing off one's professional knowledge is not generally a laugh, nor useful intelligence to those not in need.

Apparently this is a matter of opinion. I tend to prefer discussions in which at least one person actually knows what they are talking about. Kalleh asked, I answered. Sorry.

quote:

in nystagmus,which is usually pathological, the primary eye movement is an oscillation; but it swings back rapidly, and this is called a corrective saccade.

Let's be correct. The primary eye movement is a drift, and that the combination of drift and saccade produce the oscillation.

As I said, saccades can be components of pathological movements. The corrective saccade in nystagmus is a normal fixation saccade, correcting for a drift off the fixation point. The saccade is not the problem, the drift is. The saccade is the solution. Together they create a pathological condition called nystagmus. They are perfectly normal saccades as can be seen by their position on the main sequence.

Moreover, when I said "Maybe saccade used to include pathologic movements, but now it almost exclusively refers to normal eye movements" I meant the following: if you search for "saccade" in Google Scholar, it will bring up hundreds of papers about saccades. These papers are not about any old jerky eye movements, nor are they about some kind of pathology, they are specifically about a particular kind of ubiquitous time-optimal refixation movement, with a particular control signal, coming from a particular part of the brain. Med schools may have taught something different before about 1965, but that's what the word means today.

saccade – A brief, rapid movement of the eye from one position of rest to another, whether voluntary (as in reading) or involuntary (as when a point is fixated).nynstagmus – Involuntary, rapid, oscillating movement of the eyeballs (most commonly from side to side); an instance or type of this.